Gear shift mechanism for tilt cab vehicles

ABSTRACT

A gear shift mechanism for tilt cab trucks comprises a lever-receiving structure disposed on the engine/transmission structure. The lever-receiving structure includes a ball joint. The shift lever is removably received in a socket of the ball. When the cab is tilted, the lever becomes detached from the ball joint and is centered in its through-hole in the cab floor or engine hood by bands or wires and tensile springs, which are fixed or tensioned between the lever and the edges of the through-hole.

BACKGROUND OF THE INVENTION

The present invention relates to a gear shift mechanism in a motorvehicle with a cab tiltable relative to the vehicle chassis andengine/transmission, comprising a lever receiving mounting arrangedunder the cab floor of the engine hood with a bearing for a gear shiftlever, which extends into the cab through a through-hole in the floor orengine hood.

In trucks with front mounted tiltable cabs, in which the engine isusually mounted under the cab and is covered by a hood between theseats, the gear shift lever and associated linkages must be arranged sothat they do not present an obstacle to the tilting movement. Thearrangement should be such that the gear selector has distinct positionsand it should only be minimally affected by the movements of the cab,which can, in todays modern trucks with comfortable spring mounted cabs,be relatively large in all directions relative to the chassis andengine/transmission. Furthermore, the gear selector mechanism should besealed off effectively so that a low noise level can be maintained inthe cab. Finally, the gear shift mechanism should be simple and reliableand permit tilting of the cab without any additional "releasingoperations".

None of the solutions presented up to now fulfill all of theseconditions. While it is true that gear selector mechanisms with thelever mounting fixed to the transmission usually have distinct positionsand are only minimally effected by cab movements, they have eithersealing problems (in unarticulated lever designs) because the hole inthe engine hood or floor must be large or they require extra blockingmechanisms for the release means (for articulated lever designs) SwedishPatent No. 439,464.

Gear shift mechanisms with the shift lever bearing joined to the cab aresimpler to seal in order to keep the noise level low, but in this casethe shift lever must be able to somehow be released from the rest of theshift mechanism when the cab is tilted. These mechanisms are, however,affected by cab movements with indistinct gear speed positions as aresult as well as problems with the gear selector being jolted out ofgear when driving on uneven surfaces.

Gear shift mechanisms, in which the shift lever bearing is resilientlyjoined to the cab, are shown in German Patent No. 2,110,310 and U.S.Pat. No. 4,269,282, for example. In both of these mechanisms, the shiftlever has a spherical end portion which is normally received in anopening in the gear transfer mechanism. This end portion is removed fromthis opening when the cab is tilted. The spring loaded mounting of thebearing in the cab permits limited shock absorbing movement of the cabwithout any problems, but large vertical cab movements or lateralmovements present the risk that the spring loaded shift lever mountinghousing will lose contact with its stationary support surface in thegear lever socket in the engine/transmission, resulting in play,misalignment and malfunctioning. Hard and rapid gear shifting can havethe same result. Another disadvantage is that it is not possible toprovide a connection free from play between the lever and the geartransfer mechanism. In order to permit disengagement and engagement,there must be a certain amount of play between the spherical end of thelever and the complementary socket in the gear transfer mechanism. Thisplay increases with time due to wear and produces an even larger effectat the shift lever handle which produces indistinct gear selection.

The purpose of the present invention is to remove all of the abovementioned disadvantages and provide a shift mechanism of the typedescribed by way of introduction, which is simple and reliable, hasdistinct gear positions, is simple to seal off to provide low noiselevel inside the cab, and which does not require any additional releasesteps prior to tilting the cab or any engaging steps after tilting thecab back to its operating position.

SUMMARY OF THE PREFERRED EMBODIMENT

This is achieved according to the invention by virtue of the fact thatthe lever receiving mounting with associated bearing is securely mountedin the engine/transmission, that the lever is removably connected to thebearing to become detached from the bearing when there is a levermovement caused by the tilting movement of the cab, and that the leveris connected with limited mobility to the cab and, in the tiltingposition of the cab, is spring loaded to a defined disposition in thethrough-hole in the floor or engine hood.

The direct connection between the shift lever and a bearing securelyjoined to the engine/transmission provides distinct shift positions andnegligible risk of the gear selector being jolted out of gear, since theshift mechanism is not affected by the cab movements. By placing thelever connection directly in the bearing, the lever will always be inthe through-hole in the floor or engine hood regardless of the positionof the cab, thus eliminating the need for separating sealing surfaces.An undivided sealing means can be used between the lever and the edgesof the through-hole, thus making effective noise insulation possible.

The mechanism also permits comparatively large relative movements in alldirections between the cab and the engine/transmission. The cab can betilted up or down regardless of the gear selector position.

BRIEF DESCRIPTION OF THE DRAWING

The invention will be described in more detail with reference to anexample shown in the accompanying drawing, where

FIG. 1 shows a partially sectioned schematic side view of the gear shiftmechanism according to the invention, and

FIG. 2 shows a view along the line II--II in FIG. 1.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

In the Figures, 1 designates a plate constituting a wall of a part of afloor or an engine hood in a truck cab and 2 is an opening forming athrough-hole for a shift lever generally designated 3, which, in amanner to be described in more detail below, is connected to a ball 4 ofa ball joint 5 in a lever receiving mounting 6. The cab is tiltablerelative to a body of the vehicle, the vehicle including a chassis andan engine/transmission structure mounted on the chassis. The mounting 6is fixed to the vehicle engine, the transmission or some componentjoined thereto (not shown), so that there is no relative movementbetween the shift lever 3 and the transmission when there is relativemovement between the plate 1 and the engine/transmission, i.e. duringshock absorbing movements of the cab.

The gear shift lever 3 is made with a conical portion 7 and the ball 4has in it a complementary cavity or socket 8, in which the conicalportion 7 is received when the cab is in its normal untilted position.The socket 8 has an upper edge portion 8a with a larger conical anglethan the rest of the socket and two opposing planer surfaces 8b. Theconical portion 7 of the shift lever has corresponding planer surfaces7b, thus preventing rotation of the lever 3 relative to the ball. Belowthe conical portion 7, the lever has a somewhat narrower portion 9 witha pointed end 10. This is received in a tubular extension 11 of the ball4. The extension 11 ends with a short angled arm 12, which is joined viaa joint provided with a needle bearing to a shifting rod 13, connectedto the gear transfer mechanism of the transmission.

One end of each of a pair of tensile springs 15 is hooked near to thegear lever handle 14. The other ends of the springs are attached toindividual eyes 16 in the plate 1, so that in the normal untiltedposition of the cab, the lever 3 is spring loaded towards the leverreceiving mounting 6 and so that its conical portion 7 is held pressedwithout play into the socket 8. Between the lever 3 and the through-hole2, four flexible elements 17 in the form of bands or wires are attachedto a flange 18 around the through-hole 12 and in individual plates 19welded to the lever. FIG. 2 shows one of the four flexible elements 17with associated plate 19. The anchoring points for the three otherelements are designated 20.

When the cab is tilted, the lever 3 is pulled upwards by the flexibleelements 17 and is separated from the ball 4 of the ball joint. At thesame time the springs 15 load the lever downwards and keep the elements17 (the bands or wires) tensioned. Together with the springs, theelements 17 fix the lever 3 in a defined position in the hole 2 in thefloor/engine hood 1, as indicated by the dash dot lines in FIG. 1. As aresult thereof, the pointed end of the lever 3 will also have a definedposition in relation to the conical socket 8. The components have suchdimensions that the pointed end 10 of the lever 3 is guided into thesocket 8 regardless of the gear selector position, when the cab istilted back to its normal operating position. This is achieved by virtueof the fact that the wide conical portion 8a is disposed so close to thecenter of rotation of the ball 4 that its position changes very littlebetween the different gear positions.

In the embodiment described above, it is possible to use an undividedsealing bellows 21 and a common sleeve covering 22 between the edge ofthe through-hole 2 and the lever 3.

I claim:
 1. A gear shift mechanism in a motor vehicle having a body anda cab tiltable relative to said body, said body including a chassis andan engine/transmission structure supported on said chassis, a shiftlever mounted on said cab and including an upper manually grippableportion and a lower end projecting through a hole in a wall of said cab,a shift lever-receiving structure mounted on said body and comprising arotatable member including a socket which is open toward said hole insaid cab wall, said lower end of said shift lever being removablyreceived in said socket of said rotary member when said cab is in anon-tilted state, said lower end of said shift lever being slidable outof said socket when said cab is in a tilted state, and spring meansoperably connected to said shift lever for maintaining said lower end ofsaid shift lever in a predetermined position relative to said socketwhen said cab is in said tilted state in order to facilitate reinsertionof said lower end into said socket when said cab is returned to anon-tilted state.
 2. A gear shift mechanism according to claim 1including a movable shifting rod operably connected to a gear transfermechanism of said engine/transmission structure, said rotatable memberbeing operably connected to said shifting rod for moving the latter inresponse to shift lever-induced rotation of said rotatable member.
 3. Agear shift mechanism according to claim 1, wherein said rotary membercomprises a ball mounted in a spherical recess.
 4. A gear shiftmechanism according to claim 1, wherein said socket comprises a profilesocket and said shift lever includes a portion shaped correspondingly tosaid socket and fitted therein when said cab is in said non-tiltedposition.
 5. A gear shift mechanism according to claim 1, wherein saidsocket is generally conically shaped, said lower end of said shift leverincluding a generally conically shaped portion received in said socket.6. A gear shift mechanism according to claim 5, wherein a lowermost tipof said lower end of said shift lever includes a conical point forming alarger cone angle than said generally conically shaped portion.
 7. Agear shift mechanism according to claim 1 including a plurality of bandsdisposed below said hole and connecting said shift lever to said wall tocenter said shift lever relative to said hole when said cab is in saidtilted state.
 8. A gear shift mechanism according to claim 1, whereinsaid spring means is connected between said shift lever and said wall.